Alkylation of aromatic hydrocarbons



Patented July 21 1942 ALKYLATION F AROMATIC HYDRO .CARBONS Raymond E. Schaad, Chicago, Ill., asslgnor to Universal Oil Products Company, Chicago, 111., a corporation of Delaware No Drawing. Application April 30, 1941,

Serial No. 391,099

Claims.

This invention relates to the treatment of aromatic hydrocarbons to produce alkylated aromatic hydrocarbons. More'specifically it is concerned with the production of mono-alkylated and poly-alkylated aromatic hydrocarbons in the presence of a catalyst.

It is recognized that in general thecatalytic alkylation of aromatic hydrocarbons has been known for some time. However, the present invention differentiates from the prior art on this subject in the use of a particular catalytic material comprising as its active ingredient an acid phosphate of an alkaline earth metal.

In one specific embodiment the present invention comprises a process for producing alkylated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and an olefinic hydrocarbon to contact under alkylating conditions in the presence of a catalyst comprising as its active ingredient an acid phosphate of an alkaline earth metal.

Aromatic hydrocarbons, such as benzene, toluene, other alkylated benzenes, naphthalene, alkylated naphthalenes, other poly-nuclear aromatics, etc., which are alkylated by olefinic hydrocarbons as hereinafter set forth, may be obtained by the distillation of coal, by the dehydrogenation oi naphthenic hydrocarbons, by the dehydrogenation and cyclization of aliphatic hydrocarbons, alkylated aromatic hydrocarbons. and alkylated naphthenic hydrocarbons, and by other means.

Olefinic hydrocarbons utilizable as alkylating agents in the present instance comprise mono olefins and poly-olefins. Olefins which are em ployed in the present process are either normally gaseous or normally liquid and comprise ethylene and its higher homologs, both gaseous and liquid, the latter including various polymers of normally gaseous olefins, but these different olefinic hydrocarbons and those mentioned hereinafter are not necessarily equivalent in their action as alkylating agents. Cyclic olefins may also serve in alkylating aromatic hydrocarbons but generally under conditions of operation diii'erent from those employed when alkylating aromatic hydrocarbons by non-cyclic olefins, and this reaction may involve intermediate formation of olefins from cyclo-paraffins in the presence of the catalyst. Other oleflnic hydrocarbons which may be interacted with the above indicated aromatic hydrocarbons include conjugated diolefins such as butadiene and isoprene, also nonconjugated diolefins, and other poly-olefins. Oleflnic hydrocarbons utilizable as alkylating agents are present in products of thermal and catalytic cracking of oils, in those obtained by dehydrogenating paraflinic and olefinic hydrocarbons or in the products resulting from dehydrating alcohols. V

Alkylation of aromatic compounds may also be effected in the presence of catalysts hereinafter described by charging with the aromatic hydrocarbon a substance capable of producing oleflnic hydrocarbons under the operating conditions chosen for the reaction. Such olefin-producing substances include alcohols, ethers, and esters, which are capable of undergoing dehydration or splitting to olefinic hydrocarbons, containing at least two carbon atoms per molecule, which may be considered as present in the reaction mixture even though possibly as transient inter mediate compounds which react further with aromatic hydrocarbons to produce desired re action products.

Catalysts suitable for use in efi'ecting the process of the present invention comprise alkaline earth acid phosphates and particularly the mono-alkaline earth acid phosphates, also termed the dihydrophosphates, of calcium. strontium, and barium. As an example of these salts, mono-calcium phosphate is represented by the formula Ca(H2PO4 2.HcO for the hydrated salt or as CaiHzPOUz when water of hydration is absent. An acid phosphate of an alkaline earth metal may be used as such or it may be mixed with or deposited upon carriers or support-- ing materials such as silica, diatomaceous earth. alumina, silica-alumina composites, crushed porcelain, pumice, firebricir, etc.

A composite of an alkaline earth acid phosphate and a carrier in finely powdered form, after thorough mechanical mixing, may be subjected to drying, pelleting, and heating operations to produce formed particles of catalyst suitable for use as reactor packing material, or the alkaline earth acid phosphate itself .may be similarly formed into pellets or granules. A suitable carrier may also be impregnated with a selected acid phosphate to form a composite catalyst suitable foruse in promoting interaction of aromatic and oleflnic hydrocarbons. A suitable catalytic material may be prepared by adding to di-calcium phosphate or tri-calcium phosphate the calculated amount of ortho-phosphoric acid to form a composite with a composi tion corresponding to that of mono-calcium phosphate. an alkaline earth phosphate forms a catalyst of desired alkylating activity, but in general an Thus addition of phosphoric acid to acid phosphate containing no free phosphoric acid has suiiicient activity for catalyzing the process as herein described. alkylating catalysts which may be employed in the present process are not necessarily equivalent in their action.

Further, when an acid phosphate is used in connection with a carrier, the proportions of carrier and active ingredient may be varied as desired to make catalyst composites of difierent activities. Accordingly, catalytic material of appropriate activity is thus available for use with the more reactive olefins such as those containing a tertiary carbon atom as is present in isobutene, tri-methyl ethylene, etc.

There is relatively little formation of carbon or carbonaceous material upon the catalyst when the reactions between aromatic and olefinic hydrocarbons are carried out under hydrogen pressure, but carbon formation does occur to a substantial extent in the absence of hydrogen.

In effecting reaction between aromatic hydrocarbons and an alkylating agent as an olefinic hydrocarbon according to the process of the present invention, the exact method of procedure varies with the nature of the reacting constituents. A simple procedure, utilizable in the case of an aromatic hydrocarbon which is normally liquid or if solid is readily soluble or easily dispersible in a substantially inert liquid and a normally gaseous or liquid olefinic hydrocarbon, consists in contacting the aromatic and olefinic hydrocarbons with a catalyst containing an acid phosphate of an alkalineearth metal at a temperature of from about 100 to about 450 C. and preferably between about 250 and about 400 C. under a pressure up to about 100 atmospheres or more. Intimate contact of the reacting components with the catalyst is efiected by passing the reaction mixture through a fixedbed of granular or mlleted catalyst or the reacting components may be mixed with finely divided catalyst and reacted in either a batch or continuous type of operation. The hydrocarbons subjected to reaction'are preferably in the proportion of 1 molecular proportion of olefinic hydrocarbon to between about 2 and about 20 molecular proportions of aromatic hydrocarbon in order to diminish polymerization of olefinic hydrocarbons and to favor interaction of olefinic hydrocarbons with the aromatic hydrocarbons or mixture of aromatic hydrocarbons in the hydrocarbon fraction undergoing treatment.

Thus a hydrocarbon mixture comprising essentially normally liquid aromatic hydrocarbons and a fraction containing olefinic hydrocarbons are commingled and passed through a reactor containing an acid phosphate such as mono-calcium acid phosphate, or at least a portion of the arcmatic hydrocarbon. is charged to such a reactor while the fraction containing olefinic hydrocarbons, as such or preferably diluted by another portion of the aromatic hydrocarbon being treated, is introduced at various points between the inlet and the outlet of the reaction zone in such a way that the reaction mixture being contacted with the catalyst will at all times contain a relatively low proportion of the olefinic hydrocarbon and thus favor interaction of aromatic and olefinic hydrocarbons rather than polymerization of the latter.

While the method of passing the aromatic and olefinic hydrocarbons, either together or countercurrently, through a suitable reactor containing the granular catalyst is generally customary pro- The different cedure, the interaction of these hydrocarbons may also be effected in a closed vessel in which some of the reacting constituents are in liquid phase and in which the catalyst is preferably in finely divided form and maintained in dispersion or suspension by some method of agitation. The choice of operating procedure is dependent upon the circumstances such as the temperature, pressure, and activity of the catalyst found to be most effective for producing the desired reaction between particular aromatic and olefinic hydrocarbons.

Alkaline earth acid phosphates as herein described are preferred catalysts as they permit continuous reaction of aromatic and olefinic hydrocarbons in the presence of a fixed bed of catalyst and thus make it possible to avoid mechanical problems as well as oxidation and corrosion difiiculties encountered when this reaction is carried out in the presence of sulfuric acid which is sometimes used as an alkylating catalyst. Further, an acid phosphate such as calcium acid phosphate also has the advantage over aluminum chloride utilizable for the same purpose in that an acid phosphate forms substantially no addition compounds or complexes with aromatic and/or olefinic hydrocarbons .as is characteristic of catalysts containing aluminum chloride.

Reactions between olefinic and aromatic hydrocarbons in the presence of an alkaline earth acid phosphate are apparently of a relatively simple character although they may be accompanied by certain amounts of decomposition or destructive hydrogenation, the latter being in evidence particularly when the reaction is carried out under a relatively high'hydrogen pressure at a temperature of about 400 C. While the reaction is not understood completely. a typical alkylation of an aromatic hydrocarbon apparently involves the addition of an aromatic hydrocarbon to a double bond of an olefinic hydrocarbon to produce an alkylated aromatic hydrocarbon which may in turn undergo further reaction with 1 or more molecular proportions of olefinic hydrocarbon thus producing di-alkylated and poly-alkylated aromatic hydrocarbons. In case the alkylating agent is a. diolefin or other poly-olefin the interaction with an arcmatic hydrocarbon may involvenot only alkylation but possibly polymerization. Thus benzene and butadiene may give a substantial yield of phenyl butenes which polymerize to give a dimer of phenyl butene. Within certain limits it is possible to produce mainly mono-alkylated aromatic hydrocarbons by proper adjustment of catalyst activi y, ratio of aromatic to olefinic hydrocarbons, operating conditions of temperature, pressure, rate of feed of the reacting components, etc.

The reaction between an aromatic hydrocarbon and a hexene or other normally liquid olefin of higher molecular weight may involve not only addition of aromatic and olefinic hydrocarbons but also a depolymerization or splitting of the olefinic hydrocarbon into olefinic fragments of lower molecular weights which react with the aromatic hydrocarbons to produce alkylated aromatic hydrocarbons. Thus benzene and di-isobutene or tri-isobutene react and yield tertiary butyl benzene and poly-tertiary butyl benzenes, while nonene and benzene yield both butyl and amyl benzenes by so-called depoly-alkylation.

In general, the products formed by interaction of an olefinic hydrocarbon with a molal excess means as by distillation, and the unreacted portion of the aromatic hydrocarbon originally charged and generally the pqly-alkylated hydrocarbons formed are returned to the prmess and mixed with additional quantities of the oleflnic and aromatic hydrocarbons being charged to contact with the catalyst. This recycling of polyalkylated aromatic hydrocarbons sometimes aids in the production of mainly mono-alkylated aromatic hydrocarbons and depresses the formation of more-highly alkylated derivaties. The total alkylated product thus freed from the excess of the originally charged aromatic hydrocarbon is separated into desired fractions by distillation at ordinary or reduced pressure or by other suitable means.

While the process of this invention is particularly applicable to the production of alkylated aromatic hydrocarbons from aromatic and olefinic hydrocarbons, it may be utilized also in alkylating other aromatic compounds as in converting phenols and olefinic hydrocarbons into alkylated phenols using a catalyst containing an alkaline earth acid phosphaie and operating generally within the ranges of temperature and pressure hereinabove set forth.

The following examples are given to illustrate the character of results obtainable by the use of the present process, although the examples given are not introduced with the intention of unduly restricting the generally broad scope of the invention.

Example I About parts by weight of mono-ethyl benzene are formed by contacting 80 parts by weight (91 volumes) of benzene and 10 parts by weight of mono-calcium phosphate mono-hydrate with ethylene for 4 hours at 825 C. The reaction is carried out by placing the benzene and catalyst in an autoclave of 850 volumes capacity, adding ethylene thereto at 20 C. to atmospheres pressure and then adding nitrogen to a total pressure of 50 atmospheres. The autoclave so charged is then heated as above indicated, cooled. the products removed and analyzed to determine ihe'extent of reaction.

Example II The autoclave employed in Example I is charged with 80 parts by weight of benzene, parts by weight of propene, and 10 parts by weight of mono-calcium phosphate monohydrate, nitrogen is added to a pressure of atmospheres, and the autoclave is heated 4 hours at 300 C. The resulting reaction mixture contains 33 parts by weight of mono-isopropyl benzene and 4 parts by weight of higher boiling aromatic hydrocarbons.

The nature of the present invention and its commercial utility can be seen from the specification and examples given, although neither section is intended to limit its generally broad scope.

I claim as my invention:

1. A process for producing aromatic com-,

pounds having a higher number of carbon atoms per molecules than the aromatic compound from which they are derived which comprises subjecting said aromatic compound to contact with an olefinic hydrocarbon under alkylating conditions in the presence of a catalyst containing an acid phosphate of an alkaline earth metal.

2. A process for producing alkylated aromatic compounds which comprises subjecting an aromatic compound and an olefinic hydrocarbon to.

contact under alkylating conditions in the presence of a catalyst containing an acid phosphate of an alkaline earth metal.

3. A process for producing alkylated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and an olefinic hydrocarbon to contact under alkylating conditions in the presence of a catalyst comprising essentially an acid phosphate of an alkaline earth metal.

4. A process for producing alkylated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and an olefinic hydrocarbon to contact at a temperature of from about 100 to about 450 C. in the presence of a catalyst comprising essentially an acid phosphate of an alkaline earth metal.

5. A process for producing alkyiated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and an olefinic hydrocarbon to contact at a temperature of from about 100 to about 450 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of a catalyst comprising essentially an acid phosphate of an alkaline earth metal.

6. A process for producing alkylated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and an olefinic hydrocarbon to contact at a temperature of from about 100 to about 450 C. in the presence of a hydrogen-containing gas and of a catalyst comprising essentially an acid phosphate of an alkaline earth metal.

'7. A process for producing alkylated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and an olefinic hydrocarbon to contact at a temperature of from about.100 to about 450 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of a hydrogen-containing gas and a catalyst comprising essentially an acid phosphate of an alkaline earth metal.

8. A process for producing alkylated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and a normally gaseous oleflnic hydrocarbon to contact at a temperature of from about 100 to about 450 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of a catalyst comprising essentially an acid phosphate of an alkaline earth metal.

9. A process for producing alkylated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and a normally liquid olefinic hydrocarbon to contact at a temperature of from about 100 to about 450 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of a catalyst comprising essentially an acid phosphate of an alkaline earth metal.

10. A process for producing alkylated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and a normally gaseous olefinic hydrocarbon to contact at a temperature of from about 100 to about 450 C. under a presaromatic hydrocarbon and a normally liquid olefinic hydrocarbon to contact at a temperature of from about 100 to about 450 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of a hydrogen-containing gas and of a catalyst comprising essentially an acid phosphate of an alkaline earth metal.

12. A process for producing alkylated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and an oleflnic hydrocarbon to contact at a temperature of from about 100 to about 450 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of a catalyst comprising essentially a calcium acid phosphate.

13. A process for producing alkylated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and an olefinic hydrocarbon to contact at a temperature of from about 100 to about 450 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of a catalyst comprising essentially a strontium acid phosphate.

14. A process for producing alkylated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and an olefinic hydrocarbon to contact at a temperature of from about 16. A process for producing alkylated benzene which comprises subjecting benzene and an olefinic hydrocarbon to contact at a temperature of from about to about 450 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of a catalyst comprising ementially calcium dihydrophosphate.

17. A process for producing ethylated benzene which comprises subjecting benzene and ethylene to contact at a temperature or from about 100 to about 450 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of a catalyst comprising essentially calcium dihydrophosphate.

18. A process for producing propylated benzene which comprises subjecting benzene and propene to contact at a temperature of from about 100 to about 450 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of a catalyst comprising essentially calcium dihydrophosphate.

19. A process for producing alkylated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and an olefinic hydrocarbon to contact at a temperature of from about 100 to about 450 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of a hydrogen-containing gas and of a catalyst comprising essentially calcium dihydrophosphate.

20. A process for producing alkylated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and an olefinic hydrocarbon to contactat a temperature of from about 100 to about 450 C. in the presence of a catalyst comprising essentially a composite of an acid phosphate and a substantially inert carrier of an alkaline earth metal.

RAYMOND E. SCHAAD.

CERTIFICATE OF CORRECTION. I Patent No. 2,290,211. July 21, 191 2.

mamonn 2. scmum.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 11., second column, lines59andl10, claim 20, for "phosphate and a substantially f inert eerrier of an alkaline earth metal" read --phosphate ofan alkaline earth metal ande substantially inert carrier": and that the said Letters Patent ahouldbe read with this correction therein that the same may conform to the record pf the case in the Patent Office.

Signed and sealed this Btu-day of September, A. D. 1911.2.

Henry Van Arsdale, (Seal) Acting Connfiisioner of Patents. 

